Photochromic Inorganic Fluorides – PRIDE

First of all, from the fundamental breakthrough proposed with the recent thesis work of Lucile Cornu on the new fluorinated elpasolite compounds Rb2KInF6 doped with cerium, the project aims to produce photochromic paints based on these inorganic fluorides. Second, new, less expensive and more robust photochromic compositions (replacement of indium, extension of fluorides to oxides, etc.) must be developed. Modeling studies (DFT) will be useful in selecting the most promising compounds. The study of inorganic fluorides and oxides in powder form will be carried out using techniques such as X-ray diffraction, chemical titrations, scanning and transmission electron microscopies, optical spectroscopy. Finally, the photochromic powders which exhibit the best performance will be introduced into suitable polymer matrices in order to formulate UV detection paints, which can be used in this new market.

At the level of the fluorinated photo-chromo-luminescent family (elpasolite compounds that change their emission color under UV), extensive modeling has enabled us to better control their photochromic mechanism, and new compositions have made it possible to vary the colors of emission of irradiated and non-irradiated states.
A new family of oxide compounds has been proposed, optimized and painted. Gradual and irreversible coloring paints (from white to intense blue) depending on the UV dose received, make them perfectly applicable as UV indicators.

The development of paints based on inorganic oxides with particularly marked photochromism (strong optical contrast between colored state and discolored state), gradual (gradual change in color: darkening, over a wide range of UV doses) and irreversible (discoloration after exposure UV is not significant, even over very long periods of time) opens up prospects for their use as intelligent UV indicators: for packaging, as security inks, as individual indicators of solar exposure, etc.

The photochromic powders developed in collaboration between the LRCS and the ICMCB have allowed the publication of many articles in common between these two entities, as well by the production of results articles (5 peer-reviewed articles), a review on photochromic oxides (accepted). This work is associated with a doctoral thesis. Also, a patent has been filed for a new way of synthesizing these powders by the Fluomat technology transfer platform of the ICMCB. Finally, painting (intellectual property of the company OliKrom) was kept secret so that OliKrom could have the full rejuvenation of paints with significant marketing potential.

Sientific articles:
1. CaSn(OH)6 hydroxides, CaSnO3 oxides and CaSnF6 fluorides: Synthesis and structural filiation. Cationic environment impact on Pr3+ doped compounds luminescence
Gaudon, M., Salek, G., Kande, M., (...) Wattiaux, A., Jubera, V.
Journal of Solid State Chemistry, Elsevier, 2018, 265, 291–298
2. Photochromic Behavior of ZnO/MoO3 Interfaces
Andron, I., Marichez, L., Jubera, V., ...Frayret, C., Gaudon, M.
ACS applied materials & interfaces, ACS, 2020, 12(41), 46972–46980
3. Improvement of the photochromism taking place on ZnO/MoO3 combined material interfaces
Ines Andron, Léa Marichez, Véronique Jubera, Alexandre Fargues, Christine Frayret and Manuel Gaudon
Mater. Adv., RSC, 2021, 2, 782-792
4. Photo-activated emitting defects in the Ce-doped CaSnF6 fluoride.
Ines Andron, Christine Frayret, Manuel Gaudon, Alexandre Fargues, Etienne Durand, et Véronique Jubera. .
Materials Research Bulletin, Elsevier, 2021, 142, 111384.

Review : Photochromism in inorganic crystallised compounds,
Badour, Y., Jubera, V., Andron, I., Frayret, C., Gaudon, M.
Optical Materials: X, 2021, 12, 100110


Patent-2019) 19 14502 (Fr) – CNRS - Procédé de synthèse de fluorures à base d’indium et de métaux alcalins.
Inventeurs : Demourgues, A. Chiron, E. Durand, M. Gaudon, N. Penin, V. Jubera, I. Andron.

PRIDE aims to design, synthesize and shape bistable photochromic fluorides and oxides whose optical properties (absorption or emission) can be controlled in a reversible way when they are exposed to selective photon irradiation. PRIDE takes place in a context of extensive interest since our societies need high increase of UV sensors and storage information capacity for which the developing of new generation of switchable and bistable materials is a main target.
The scientific challenge is double. Firstly, starting from the fundamental breakthrough proposed by our team with the recent thesis works of Lucile Cornu on new photochromic cerium-doped Rb2KInF6 compounds, the project aims to produce photochromic paints based on these inorganic fluorides. Secondly, in parallel studies, new photochromic powders with less costly and more robust composition (replacement of indium, extension from fluorides to oxides, etc…) have to merge from new research developments. Modeling investigations (DFT & beyond) will be helpful to select the most promising candidates at the beginning of the project.
The study of the inorganic fluorides and oxides in powder shape will be performed using techniques such as X-ray diffraction, chemical titrations, scanning and transmission microscopies and optical spectroscopy. Fluoride or oxide powders production at large scale (100 g – 1 kg per batch) will be produced in order to be formulated in paints whose final optical performances will be tested depending on various industrial requirements (UV dosimeters, storage information layers, etc…).
Finally, the obtained results will be patented, published and/or presented in international congress depending on the most adequate route basing on our elaborated consortium agreement and taking firstly into account the balance between the gains for socio-economic and academic impacts.
To reach these aims, four partners with complementary skills form the PRIDE consortium: solid state chemists (Partner 1), physical chemists (Partner 2), powder manufacturer (Partner 3) and paints formulator (Partner 4). Partner 1 (ICMCB-cnrs) will take charge of the synthesis and physico-chemical characterization of the photochromic powder. Partner 2 (LRCS) will be in charge of the DFT calculations. Partner 3 (Fluomat spin-off) will synthesize at large scale the fluoride and oxide powders while Partner 4 (Olikrom), industrial partner specialized in X-chromic paints will managed the paints production and their coating in various substrates.
Grants for one PhD student and two Master students located in the two academic partners, and support for three engineers in respectively Fluomat and Olikrom is finally required.

Keywords: Photochromic, Switch, Smart/Functional, Luminescence, Inorganic Fluorides/Oxides, Paints, Sensors, Data storage